Does a state-based action check happen in the middle of resolving a spell or only after it fully resolves?

State-based actions (SBAs) are checked only at specific moments: whenever a player would receive priority, which happens after a spell or ability has finished resolving — not during it. This is established in CR 117.5 and CR 704.3.

CR 704.3 states that state-based actions are checked and performed as a player is about to receive priority. Since no player receives priority in the middle of a spell or ability resolving (CR 117.4), no SBA check occurs until resolution is complete.

This matters most for effects that temporarily put creatures into illegal states mid-resolution. For example, if a spell says 'deal 3 damage to each creature, then each player draws a card,' a creature reduced to 0 toughness by the damage does not die before the draw happens — the entire spell resolves first, then SBAs are checked, and then the creature is moved to the graveyard.

Similarly, if a single spell creates a token and simultaneously gives it a lethal power/toughness combination, the token won't be destroyed until after the spell fully resolves and SBAs are checked.

The key principle: resolution is an uninterrupted process (CR 608.2). Only once the spell or ability is done and a player is about to receive priority does the game check for creatures with 0 or less toughness, planeswalkers with 0 loyalty, and all other state-based actions (CR 704.5).